Chartpak AD Markers are now available in 2 distinctive nib styles, The Tri Nib which has been the mainstay of the line for many years, and the new Fine Point Nib. The Tri Nib has three distinct line weights in one nib! brilliant color in fine point, medium weight or broad strokes - with just a twist of the wrist. The unique shape of the Tri-Nib gives you precise control over your stroke, and the wide palette of permanent colors, which includes a complete range of past els and grays, opens new worlds of creative possibility. The Fine Point Nib markers feature a new precision nib for detail work, lettering and outlining. Available in 25 of the most popular colors, with the same non-toxic, solvent based formula. The Tri -Nib Colorless Blender produces graduation/color from deep tones to light. From crisply articulated tight comps to broadly expressive illustrations, all the line you need is right at your fingertips! Chartpak AD Markers are xylene based.